<PAGE>

                                                                  Exhibit 10.101
                                 AMENDMENT THREE

         AMENDMENT THREE (this "AMENDMENT") dated as of August 17, 2000 by and
among, (i) COLLINS HOLDINGS EME, LLC ("COLLINS HOLDINGS"), (ii) COLLINS TRUST I,
as the Owner Lessor, (iii) WILMINGTON TRUST COMPANY, as the Owner Trustee, (iv)
COLLINS GENERATION I, LLC, as the Owner Participant, (v) EDISON MISSION MIDWEST
HOLDING CO. ("HOLDINGS"), (vi) MIDWEST GENERATION, LLC ("MIDWEST"), (vii)
MIDWEST FUNDING LLC ("FUNDING LLC"), (viii) BAYERISCHE LANDESBANK INTERNATIONAL
S.A., as the Midwest LC Issuer, (ix) BAYERISCHE LANDESBANK GIROZENTRALE, as the
RCE LC Issuer and (x) CITIBANK, N.A., as Holder Representative.

                  WHEREAS, Collins Holdings, the Owner Lessor, Owner Trustee,
the Owner Participant, Holdings, Midwest, Funding LLC, the Midwest LC Issuer,
the RCE LC Issuer and the Holder Representative have entered into that certain
Participation Agreement (T1), dated as of December 15, 1999 (as heretofore
amended, modified and supplemented, the "PARTICIPATION AGREEMENT"), which set
forth, INTER ALIA, certain covenants of Holdings;

                  WHEREAS, Midwest desires to enter into the Powerton/Joliet
Lease Transaction (as defined herein); and

                  WHEREAS, Midwest has requested, and Collins Holdings, the
Owner Lessor, Owner Trustee, Owner Participant, Holdings, Funding LLC, the
Midwest LC Issuer, the RCE LC Issuer and the Holder Representative have agreed,
to amend and waive certain provisions of the Participation Agreement so as to
permit the Powerton/Joliet Lease Transaction;

                  WHEREAS, the parties hereto are willing to permit Midwest to
enter into the Powerton/Joliet Lease Transaction on the terms and conditions of
this Amendment;

                  WHEREAS, Midwest and ComEd have entered into Amendment No. 1
To The Power Purchase Agreement dated as of December 15, 1999 attached as
Exhibit C, (the "Amendment No.1 to the Collins PPA") in order to provide gas
price

                AMENDMENT THREE TO PARTICIPATION AGREEMENT (T1)
<PAGE>

protection to Midwest and an adjustment to the maximum power purchase require-
ment of ComEd in connection with Midwest's sale of energy from the Facility;

                  WHEREAS, the consent of the Owner Lessor, Funding LLC and the
Holder Representative is a condition to the execution and delivery of the
Amendment No.1 to the Collins PPA, Midwest has requested and the Lenders party
hereto consent to Midwest's execution and delivery of Amendment No.1 to the
Collins PPA;

                  NOW, THEREFORE, the parties hereto agree as follows:

                  Section 1. DEFINITIONS. Except as otherwise defined in this
Amendment, terms defined in the Participation Agreement are used herein (and in
the introductions and recitals hereto) as defined therein.

                  Section 2. AMENDMENT TO THE PARTICIPATION AGREEMENT. Subject
to the satisfaction of the conditions precedent specified in Section 5 below,
but effective as of the Amendment Effective Date, the Participation Agreement
shall be amended as follows:

         (a) APPENDIX A to the Participation Agreement shall be amended by
adding the following definitions:

                  ""COMED JOLIET LEASE CONSENT I" means the Consent to Sale of
                  Assets between Midwest, ComEd and Joliet Trust I referred to
                  in the Joliet Lease Operative Documents.

                  "COMED JOLIET LEASE CONSENT II" means the Consent to Sale of
                  Assets between Midwest, ComEd and Joliet Trust II referred to
                  in the Joliet Lease Operative Documents.

                  "COMED POWERTON LEASE CONSENT I" means the Consent to Sale of
                  Assets between Midwest, ComEd and Powerton Trust I referred to
                  in the Powerton Lease Operative Documents.

                  "COMED POWERTON LEASE CONSENT II" means the Consent to Sale of
                  Assets between Midwest, ComEd and Powerton Trust II referred
                  to in the Powerton Lease Operative Documents.


                                       -2-
<PAGE>

                  "COMED POWERTON/JOLIET LEASE CONSENTS" means, collectively,
                  ComEd Joliet Lease Consent I, ComEd Joliet Lease Consent II,
                  ComEd Powerton Lease Consent I and ComEd Powerton Lease
                  Consent II.

                  "JOLIET EQUITY FINANCING PARTIES I" means, collectively, the
                  Equity Investor, the Owner Participant and the OP Guarantor
                  (each defined in the Joliet Lease Participation Agreement
                  (T1)).

                  "JOLIET EQUITY FINANCING PARTIES II" means, collectively, the
                  Equity Investor, the Owner Participant and the OP Guarantor
                  (each as defined in the Joliet Lease Participation Agreement
                  (T2)).

                  "JOLIET FACILITY" means the Joliet Station, Units 7 and 8,
                  1044 megawatts of the 1358 megawatt coal-fired electric
                  generating facility and certain related assets located in Will
                  County, Illinois and more fully described in Exhibit B to each
                  of Joliet Leases.

                  "JOLIET GUARANTEE (T1)" means the Guaranty Agreement dated as
                  of August 17, 2000 made by Edison Mission Energy in favor of
                  Joliet Trust I that, among other things, guarantees the
                  payment by Midwest of all Joliet Lease Liabilities (T1)
                  payable to Joliet Trust I.

                  "JOLIET GUARANTEE (T2)" means the Guaranty Agreement dated as
                  of August 17, 2000 made by Edison Mission Energy in favor of
                  Joliet Trust II that, among other things, guarantees the
                  payment by Midwest of all Joliet Lease Liabilities (T2)
                  payable to Joliet Trust II.

                  "JOLIET GUARANTEE (T1: EQUITY FINANCING PARTIES)" means the
                  Guaranty Agreement dated as of August 17, 2000 made by Edison
                  Mission Energy in favor of the Joliet Equity Financing Parties
                  I that, among other things, guarantees the payment by Midwest
                  of certain Joliet Lease Liabilities (T1) payable to Joliet
                  Lease Financing Parties I.

                  "JOLIET GUARANTEE (T2: EQUITY FINANCING PARTIES)" means the
                  Guaranty Agreement dated as of August 17, 2000 made by Edison
                  Mission Energy in favor of the Joliet Equity Financing Parties
                  II that, among


                                       -3-
<PAGE>

                  other things, guarantees the payment by Midwest of certain
                  Joliet Lease Liabilities (T2) payable to Joliet Lease
                  Financing Parties II.

                  "JOLIET GUARANTEES" means, collectively, the Joliet Guarantee
                  (T1), the Joliet Guarantee (T2), the Joliet Guarantee (T1:
                  Equity Financing Parties), the Joliet Guarantee (T2: Equity
                  Financing Parties), the Joliet Reimbursement Agreement (T1)
                  and the Joliet Reimbursement Agreement (T2).

                  "JOLIET INTERCOMPANY NOTE PLEDGE AGREEMENT (T1)" means the
                  Pledge Agreement (T1) dated as of August 17, 2000 between
                  Midwest and the Holdings Collateral Agent relating to the
                  pledge of the Joliet Lease Intercompany Note (T1).

                  "JOLIET INTERCOMPANY NOTE PLEDGE AGREEMENT (T2)" means the
                  Pledge Agreement (T2) dated as of August 17, 2000 between
                  Midwest and the Holdings Collateral Agent relating to the
                  pledge of the Joliet Lease Intercompany Note (T2).

                  "JOLIET LEASE (T1)" means the Facility Lease Agreement (T1)
                  dated as of August 17, 2000 between Midwest and Joliet Trust
                  I.

                  "JOLIET LEASE (T2)" means the Facility Lease Agreement (T2)
                  dated as of August 17, 2000 between Midwest and Joliet Trust
                  II.

                  "JOLIET LEASE INTERCOMPANY NOTE (T1)" means the EME Note (as
                  defined in the Joliet Lease Participation Agreement (T1))
                  dated the Closing Date (as defined in the Joliet Lease
                  Participation Agreement (T1)) evidencing the loan by Midwest
                  to Edison Mission Energy of the proceeds of the Joliet Lease
                  Transaction (T1).

                  "JOLIET LEASE INTERCOMPANY NOTE (T2)" means the EME Note (as
                  defined in the Joliet Lease Participation Agreement (T2))
                  dated the Closing Date (as defined in the Joliet Lease
                  Participation Agreement (T2)) evidencing the loan by Midwest
                  to Edison Mission Energy of the proceeds of the Joliet Lease
                  Transaction (T2).


                                       -4-
<PAGE>

                  "JOLIET LEASE INTERCOMPANY NOTES" means, collectively, the
                  Joliet Lease Intercompany Note (T1) and the Joliet
                  Intercompany Note (T2).

                  "JOLIET LEASE LIABILITIES" means, collectively, the Joliet
                  Lease Liabilities (T1) and the Joliet Lease Liabilities (T2).

                  "JOLIET LEASE LIABILITIES (T1)" mean the basic rent, the
                  supplemental rent, termination value or any other amount,
                  liability or obligation that Midwest is obligated to pay under
                  the Joliet Lease (T1) or the other Joliet Lease Operative
                  Documents (T1).

                  "JOLIET LEASE LIABILITIES (T2)" mean the basic rent, the
                  supplemental rent, termination value or any other amount,
                  liability or obligation that Midwest is obligated to pay under
                  the Joliet Leases (T2) or the other Joliet Lease Operative
                  Documents (T2).

                  "JOLIET LEASE OPERATIVE DOCUMENTS" means, collectively, the
                  Joliet Lease Operative Documents (T1) and the Joliet Lease
                  Operative Documents (T2).

                  "JOLIET LEASE OPERATIVE DOCUMENTS (T1)" means, collectively,
                  the Operative Documents as defined in the Joliet Lease
                  Participation Agreement (T1).

                  "JOLIET LEASE OPERATIVE DOCUMENTS (T2)" means, collectively,
                  the Operative Documents as defined in the Joliet Lease
                  Participation Agreement (T2).

                  "JOLIET LEASE PARTICIPATION AGREEMENT (T1)" means the
                  Participation Agreement (T1) dated as of August 17, 2000 by
                  and among Midwest, Edison Mission Energy, Joliet Trust I,
                  Wilmington Trust Company, Joliet Generation I, the Lease
                  Indenture Trustee named therein and the Pass Through Trustees
                  named therein.

                  "JOLIET LEASE PARTICIPATION AGREEMENT (T2)" means the
                  Participation Agreement (T2) dated as of August 17, 2000 by
                  and among Midwest, Edison Mission Energy, Joliet Trust II,
                  Wilmington Trust Company,


                                       -5-
<PAGE>

                  Joliet Generation II, the Lease Indenture Trustee named
                  therein and the Pass Through Trustees named therein.

                  "JOLIET LEASE PARTICIPATION AGREEMENTS" means, collectively,
                  the Joliet Lease Participation Agreement (T1) and the Joliet
                  Lease Participation Agreement (T2).

                  "JOLIET LEASE TRANSACTION (T1)" means the transactions
                  pursuant to the Joliet Lease Participation Agreement (T1) and
                  the Joliet Lease Operative Documents (T1) whereby Midwest
                  sells a 63.6% undivided interest in the Joliet Facility to
                  Joliet Trust I and Joliet Trust I leases such undivided
                  interest to Midwest pursuant to the Joliet Lease (T1).

                  "JOLIET LEASE TRANSACTION (T2)" means the transactions
                  pursuant to the Joliet Lease Participation Agreement (T2) and
                  the Joliet Lease Operative Documents (T2) whereby Midwest
                  sells a 36.4% undivided interest in the Joliet Facility to
                  Joliet Trust II and Joliet Trust II leases such undivided
                  interest to Midwest pursuant to the Joliet Lease (T2).

                  "JOLIET LEASE TRANSACTIONS" means, collectively, the Joliet
                  Lease Transaction (T1) and the Joliet Lease Transaction (T2).

                  "JOLIET LEASE TRUSTS" means, collectively, Joliet Trust I and
                  Joliet Trust II.

                  "JOLIET LEASES" means, collectively, the Joliet Lease (T1) and
                  Joliet Lease (T2).

                  "JOLIET REIMBURSEMENT AGREEMENT (T1)" means the Reimbursement
                  Agreement (T1) dated as of August 17, 2000 between Edison
                  Mission Energy and Midwest.

                  "JOLIET REIMBURSEMENT AGREEMENT (T2)" means the Reimbursement
                  Agreement (T2) dated as of August 17, 2000 between Edison
                  Mission Energy and Midwest.

                  "JOLIET SUBORDINATION AGREEMENT (T1)" means the Subordination
                  Agreement dated as of August 17, 2000 between Joliet Trust I,
                  the


                                       -6-
<PAGE>

                  Owner Participant (as defined in the Joliet Participation
                  Agreement (T1)), the Lease Indenture Trustee (as defined in
                  the Joliet Participation Agreement (T1)) and the Holdings
                  Collateral Agent.

                  "JOLIET SUBORDINATION AGREEMENT (T2)" means the Subordination
                  Agreement dated as of August 17, 2000 between Joliet Trust II,
                  the Owner Participant (as defined in the Joliet Participation
                  Agreement (T2)), the Lease Indenture Trustee (as defined in
                  the Joliet Participation Agreement (T2)) and the Holdings
                  Collateral Agent.

                  "JOLIET TRUST I" means Joliet Trust I, a Delaware business
                  trust.

                  "JOLIET TRUST II" means Joliet Trust II, a Delaware business
                  trust.

                  "POWERTON EQUITY FINANCING PARTIES I" means, collectively, the
                  Equity Investor, the Owner Participant and the OP Guarantor
                  (each as defined in the Powerton Lease Participation Agreement
                  (T1)).

                  "POWERTON EQUITY FINANCING PARTIES II" means, collectively,
                  the Equity Investor, the Owner Participant and the OP
                  Guarantor (each as defined in the Powerton Lease Participation
                  Agreement (T2))

                  "POWERTON FACILITY" means the Powerton Station, 1,538 Megawatt
                  Coal Fired Electric Generating Plant and certain related
                  assets located in Tazewell County, Illinois and more fully
                  described in Exhibit B to each of Powerton Leases.

                  "POWERTON GUARANTEE (T1)" means the Guaranty Agreement dated
                  as of August 17, 2000 made by Edison Mission Energy in favor
                  of Powerton Trust I that, among other things, guarantees the
                  payment by Midwest of all Powerton Lease Liabilities (T1)
                  payable to Powerton Trust I.

                  "POWERTON GUARANTEE (T2)" means the Guaranty Agreement dated
                  as of August 17, 2000 made by Edison Mission Energy in favor
                  of Powerton Trust II that, among other things, guarantees the
                  payment by Midwest of all Powerton Lease Liabilities (T2)
                  payable to Powerton Trust II.


                                       -7-
<PAGE>

                  "POWERTON GUARANTEE (T1: EQUITY FINANCING PARTIES)" means the
                  Guaranty Agreement dated as of August 17, 2000 made by Edison
                  Mission Energy in favor of the Powerton Equity Financing
                  Parties I that, among other things, guarantees the payment by
                  Midwest of certain Powerton Lease Liabilities (T1) payable to
                  Powerton Equity
                  Financing Parties I.

                  "POWERTON GUARANTEE (T2: EQUITY FINANCING PARTIES)" means the
                  Guaranty Agreement dated as of August 17, 2000 made by Edison
                  Mission Energy in favor of the Powerton Equity Financing
                  Parties II that, among other things, guarantees the payment by
                  Midwest of certain Powerton Lease Liabilities (T2) payable to
                  Powerton Equity
                  Financing Parties II.

                  "POWERTON GUARANTEES" means, collectively, the Powerton
                  Guarantee (T1), the Powerton Guarantee (T2), the Powerton
                  Guarantee (T1: Equity Financing Parties), the Powerton
                  Guarantee (T2: Equity Financing Parties), the Powerton
                  Reimbursement Agreement (T1) and the Powerton Reimbursement
                  Agreement (T2).

                  "POWERTON INTERCOMPANY NOTE PLEDGE AGREEMENT (T1)" means the
                  Pledge Agreement (T1) dated as of August 17, 2000 among
                  Midwest and the Holdings Collateral Agent relating to the
                  pledge of the Powerton Lease Intercompany Note (T1).

                  "POWERTON INTERCOMPANY NOTE PLEDGE AGREEMENT (T2)" means the
                  Pledge Agreement (T2) dated as of August 17, 2000 among
                  Midwest and the Holdings Collateral Agent relating to the
                  pledge of the Powerton Lease Intercompany Note (T2).

                  "POWERTON LEASE (T1)" means the Facility Lease Agreement (T1)
                  dated as of August 17, 2000 between Midwest and Powerton Trust
                  I.

                  "POWERTON LEASE (T2)" means the Facility Lease Agreement (T2)
                  dated as of August 17, 2000 between Midwest and Powerton Trust
                  II.

                  "POWERTON LEASE INTERCOMPANY NOTE (T1)" means the EME Note (as
                  defined in the Powerton Lease Participation Agreement (T1))
                  dated


                                       -8-
<PAGE>

                  the Closing Date (as defined in the Powerton Lease
                  Participation Agreement (T1)) evidencing the loan by Midwest
                  to Edison Mission Energy of the proceeds of the Powerton Lease
                  Transaction (T1).

                  "POWERTON LEASE INTERCOMPANY NOTE (T2)" means the EME Note (as
                  defined in the Powerton Lease Participation Agreement (T2))
                  dated the Closing Date (as defined in the Powerton Lease
                  Participation Agreement (T2)) evidencing the loan by Midwest
                  to Edison Mission Energy of the proceeds of the Powerton Lease
                  Transaction (T2).

                  "POWERTON LEASE INTERCOMPANY NOTES" means, collectively, the
                  Powerton Lease Intercompany Note (T1) and the Powerton Lease
                  Intercompany Note (T2).

                  "POWERTON LEASE LIABILITIES" means, collectively, the Powerton
                  Lease Liabilities (T1) and the Powerton Lease Liabilities
                  (T2).

                  "POWERTON LEASE LIABILITIES (T1)" mean the basic rent, the
                  supplemental rent, termination value or any other amount,
                  liability or obligation that Midwest is obligated to pay
                  under the Powerton Lease (T1) or the other Powerton Lease
                  Operative Documents (T1).

                  "POWERTON LEASE LIABILITIES(T2)" mean the basic rent, the
                  supplemental rent, termination value or any other amount,
                  liability or obligation that Midwest is obligated to pay under
                  the Powerton Leases (T2) or the other Powerton Lease Operative
                  Documents (T2).

                  "POWERTON LEASE OPERATIVE DOCUMENTS" means, collectively, the
                  Powerton Lease Operative Documents (T1) and the Powerton Lease
                  Operative Documents (T2).

                  "POWERTON LEASE OPERATIVE DOCUMENTS (T1)" means, collectively,
                  the Operative Documents as defined in the Powerton Lease
                  Participation Agreement (T1).

                  "POWERTON LEASE OPERATIVE DOCUMENTS (T2)" means, collectively,
                  the Operative Documents as defined in the Powerton Lease
                  Participation Agreement (T2).


                                       -9-
<PAGE>

                  "POWERTON LEASE PARTICIPATION AGREEMENT (T1)" means the
                  Participation Agreement (T1) dated as of August 17, 2000 by
                  and among Midwest, Edison Mission Energy, Powerton Trust I,
                  Wilmington Trust Company, Powerton Generation I, the Lease
                  Indenture Trustee named therein and the Pass Through Trustees
                  named therein.

                  "POWERTON LEASE PARTICIPATION AGREEMENT (T2)" means the
                  Participation Agreement (T2) dated as of August 17, 2000 by
                  and among Midwest, Edison Mission Energy, Powerton Trust II,
                  Wilmington Trust Company, Powerton Generation II, the Lease
                  Indenture Trustee named therein and the Pass Through Trustees
                  named therein.

                  "POWERTON LEASE PARTICIPATION AGREEMENTS" means, collectively,
                  the Powerton Lease Participation Agreement (T1) and the
                  Powerton Lease Participation Agreement (T2).

                  "POWERTON LEASE TRANSACTION (T1)" means the transactions
                  pursuant to the Powerton Lease Participation Agreement (T1)
                  and the Powerton Lease Operative Documents (T1) whereby
                  Midwest sells a 63.6% undivided interest in the Powerton
                  Facility to Powerton Trust I and Powerton Trust I leases such
                  undivided interest to Midwest pursuant to the Powerton Lease
                  (T1).

                  "POWERTON LEASE TRANSACTION (T2)" means the transactions
                  pursuant to the Powerton Lease Participation Agreement (T2)
                  and the Powerton Lease Operative Documents (T2) whereby
                  Midwest sells a 36.4% undivided interest in the Powerton
                  Facility to Powerton Trust II and Powerton Trust II leases
                  such undivided interest to Midwest pursuant to the Powerton
                  Lease (T2).

                  "POWERTON LEASE TRANSACTIONS" means, collectively, the
                  Powerton Lease Transaction (T1) and the Powerton Lease
                  Transaction (T2).

                  "POWERTON LEASE TRUSTS" means, collectively, Powerton Trust I
                  and Powerton Trust II.

                  "POWERTON LEASES" means, collectively, the Powerton Lease (T1)
                  and Powerton Lease (T2).


                                      -10-
<PAGE>

                  "POWERTON REIMBURSEMENT AGREEMENT (T1)" means the
                  Reimbursement Agreement (T1) dated as of August 17, 2000
                  between Edison Mission Energy and Midwest.

                  "POWERTON REIMBURSEMENT AGREEMENT (T2)" means the
                  Reimbursement Agreement (T2) dated as of August 17, 2000
                  between Edison Mission Energy and Midwest.

                  "POWERTON SUBORDINATION AGREEMENT (T1)" means the
                  Subordination Agreement dated as of August 17, 2000 between
                  Powerton Trust I, the Owner Participant (as defined in the
                  Powerton Participation Agreement (T1)), the Lease Indenture
                  Trustee (as defined in the Powerton Participation Agreement
                  (T1)) and the Holdings Collateral Agent.

                  "POWERTON SUBORDINATION AGREEMENT (T2)" means the
                  Subordination Agreement dated as of August 17, 2000 between
                  Powerton Trust II, the Owner Participant (as defined in the
                  Powerton Participation Agreement (T2)), the Lease Indenture
                  Trustee (as defined in the Powerton Participation Agreement
                  (T2)) and the Holdings Collateral Agent.

                  "POWERTON TRUST I" means Powerton Trust I, a Delaware business
                  trust.

                  "POWERTON TRUST II" means Powerton Trust II, a Delaware
                  business trust.

                  "POWERTON/JOLIET INTERCOMPANY NOTE PLEDGE AGREEMENT" means,
                  collectively, the Powerton Intercompany Note Pledge Agreement
                  (T1), the Powerton Intercompany Note Pledge Agreement (T2),
                  the Joliet Intercompany Note Pledge Agreement (T1) and the
                  Joliet Intercompany Note Pledge Agreement (T2).

                  "POWERTON/JOLIET LEASE ASSETS" means, collectively, the
                  Powerton Facility and the Joliet Facility.


                                      -11-
<PAGE>

                  "POWERTON/JOLIET LEASE GUARANTEES" means, collectively, the
                  Powerton Guarantees and the Joliet Guarantees.

                  "POWERTON/JOLIET LEASE INTERCOMPANY NOTES" means,
                  collectively, the Powerton Lease Intercompany Notes and the
                  Joliet Lease Intercompany Notes.

                  "POWERTON/JOLIET LEASE INTERCOMPANY NOTE PAYMENTS" mean the
                  payments by Edison Mission Energy to Midwest under or in
                  respect of the Powerton/Joliet Lease Intercompany Notes.

                  "POWERTON/JOLIET LEASE LIABILITIES" means, collectively, the
                  Powerton Lease Liabilities and the Joliet Lease Liabilities.

                  "POWERTON/JOLIET LEASE OPERATIVE DOCUMENTS" means,
                  collectively, the Powerton Lease Operative Documents and the
                  Joliet Lease Operative Documents.

                  "POWERTON/JOLIET LEASE PARTICIPATION AGREEMENTS" means,
                  collectively, the Powerton Lease Participation Agreement (T1),
                  Powerton Lease Participation Agreement (T2), Joliet Lease
                  Participation Agreement (T1) and Joliet Lease Participation
                  Agreement (T2).

                  "POWERTON/JOLIET LEASE TRANSACTION" means, collectively, the
                  Powerton Lease Transaction and the Joliet Lease Transaction.

                  "POWERTON/JOLIET LEASES" means, collectively, Powerton Leases
                  and Joliet Leases.

                  "POWERTON/JOLIET SUBORDINATION AGREEMENTS" means,
                  collectively, the Powerton Subordination Agreement (T1), the
                  Powerton Subordination Agreement (T2), the Joliet
                  Subordination Agreement (T1) and the Joliet Subordination
                  Agreement (T2).

                  "POWERTON/JOLIET LEASE TRUSTS" means, collectively, the
                  Powerton Lease Trusts and the Joliet Lease Trusts.".


                                      -12-
<PAGE>

         (b) APPENDIX A of the Participation Agreement shall be further amended
by deleting the definitions of "CASH FLOW AVAILABLE FOR FIXED CHARGES", "DEBT TO
CAPITAL RATIO", "FIXED CHARGES", "OPERATING EXPENSES" and "SECURITY DOCUMENTS"
in their entirety and replacing them with the following definitions:

                  ""CASHFLOW AVAILABLE FOR FIXED CHARGES" means, in respect of
                  any period, the excess, if any, of Revenues (excluding (i)
                  proceeds of any permitted asset sale, (ii) amounts available
                  in the Cashflow Recapture Fund, (iii) Synthetic Lease
                  Intercompany Note Payments and (iv) Powerton/Joliet
                  Intercompany Note Payments) during such period OVER Operating
                  Expenses during such period.

                  "DEBT TO CAPITAL RATIO" means, with respect to Holdings and
                  its Consolidated Subsidiaries, the ratio as of the end of the
                  last Fiscal Quarter for which financial statements referred to
                  in SECTION 7.1 are available of (i) the aggregate principal
                  amount of Indebtedness of Holdings and its Consolidated
                  Subsidiaries (other than Indebtedness of Holdings incurred
                  pursuant to SECTION 8.1(b)(iii), SECTION 8.1(b)(iv) and
                  SECTION 8.1(i) then outstanding to (ii) Total Capitalization
                  (excluding, to the extent included, the Synthetic Lease
                  Intercompany Note, payments by Edison Mission Energy pursuant
                  to the Synthetic Lease Guarantee, the Powerton/Joliet
                  Intercompany Notes and payments by Edison Mission Energy
                  pursuant to the Powerton/Joliet Guarantees).

                  "FIXED CHARGES" means, in respect of any period, an amount
                  equal to the aggregate of, without duplication, (i) all
                  interest due and payable on the Loans PLUS or MINUS any net
                  amount due and payable in respect of Interest Rate Hedging
                  Transactions during such period, including (A) all capitalized
                  interest and (B) the interest portion of any deferred payment
                  obligation, (ii) amounts due and payable under SECTIONS 3.3.1
                  and 3.3.2 of the Holdings Credit Agreement during such period,
                  (iii) amounts due and payable to the Lenders with respect to
                  the deduction of withholding tax on such payments pursuant to
                  SECTION 4.7 of the Holdings Credit Agreement during such
                  period, (iv) the interest portion of any deferred payment
                  obligation due and payable during such period, (v) the
                  aggregate amount of the Lease Obligations due and payable
                  during such period, and (vi) all other amounts due


                                      -13-
<PAGE>

                  and payable by the Loan Parties with respect to Indebtedness
                  (other than Designated Lease Liabilities, Synthetic Lease
                  Liabilities and Powerton/Joliet Lease Liabilities) permitted
                  under SECTION 8.1 during such period.

                  "OPERATING EXPENSES" means, in respect of any period, all cash
                  amounts paid by the Holdings Loan Parties in the conduct of
                  their business during such period, including premiums for
                  insurance policies, fuel supply and transportation costs,
                  utilities, costs of maintaining, renewing and amending
                  Governmental Approvals, franchise, licensing, property, real
                  estate and income taxes, sales and excise taxes, general and
                  administrative expenses, employee salaries, wages and other
                  employment-related costs, business management and
                  administrative services fees, fees for letters of credit,
                  surety bonds and performance bonds, Necessary Capital
                  Expenditures and all other fees and expenses necessary for the
                  continued operation and maintenance of the Generating Assets
                  and the conduct of the business of the Holdings Loan Parties.
                  Operating Expenses shall exclude (to the extent included)
                  Lease Obligations, Synthetic Lease Liabilities (other than
                  payments of Synthetic Lease Environmental Indemnity
                  Obligations) and Powerton/Joliet Lease Liabilities and shall
                  include (to the extent excluded) Designated Lease Liabilities
                  (other than Lease Obligations).

                  "SECURITY DOCUMENTS" means (i) the Collateral Agency and
                  Intercreditor Agreement, (ii) the Holdings Guarantee, (iii)
                  each Pledge Agreement, (iv) the Powerton/Joliet Intercompany
                  Note Pledge Agreements, (v) the Powerton/Joliet Subordination
                  Agreements and (vi) any other agreement or instrument
                  hereafter entered into by Holdings or any other Person which,
                  directly or indirectly, guarantees or secures payment of the
                  indebtedness evidenced by the Notes or payment or performance
                  of any other obligation.".

         (c) SECTION 7 of the Participation Agreement shall be amended by adding
Section 7.7 as follows:

                  "SECTION 7.7 POWERTON/JOLIET INTERCOMPANY NOTES. As soon as
                  possible after the end of each Fiscal Quarter, Holdings shall
                  provide


                                      -14-
<PAGE>

                  to the Holder Representative an Officer's Certificate stating
                  the outstanding principal amounts of each of the
                  Powerton/Joliet Intercompany Notes and a statement of
                  transactions reconciling such amounts to the previous Fiscal
                  Quarter end.".

         (d) SECTION 8.1(b) of the Participation Agreement shall be amended by
deleting Section 8.1(b) of the Participation Agreement and replacing it in its
entirety with the following:

                  "(b)(i) Capitalized Lease Liabilities and Operating Lease
                  Liabilities outstanding (or anticipated to be outstanding) on
                  the Closing Date and set forth on SCHEDULE 8.2.1(a) to the
                  Holdings Credit Agreement, (ii) Capitalized Lease Liabilities
                  and Operating Lease Liabilities entered into after the Closing
                  Date in the ordinary course of business not to exceed at any
                  time an aggregate principal amount equal to $50,000,000, (iii)
                  Synthetic Lease Liabilities and (iv) Powerton/Joliet Lease
                  Liabilities;".

         (e) SECTION 8.2 of the Participation Agreement shall be amended by (i)
deleting SECTION 8.2(n) of the Participation Agreement and replacing it in its
entirety with the following:

                  "(n) Liens created pursuant to the Synthetic Lease Basic
                  Documents, Powerton/Joliet Lease Operative Documents and the
                  Powerton/Joliet Intercompany Note Pledge Agreement.".

         (f) SECTION 8.4 of the Participation Agreement shall be amended by
deleting SECTION 8.4(iv) and SECTION 8.4(v) of the Participation Agreement and
replacing them in their entirety with the following subsections:

                  "(iv) transfer certain railcars or rights to railcars as part
                  of the Transco Transaction, (v) sell Synthetic Lease Assets to
                  Synthetic Lease Trust pursuant to the Synthetic Lease Basic
                  Documents and (vi) sell the Powerton/Joliet Assets and lease
                  the associated Ground Interests (as defined in the
                  Powerton/Joliet Operative Documents) to the Powerton/Joliet
                  Lease Trusts pursuant to the Powerton/Joliet Lease Operative
                  Documents; PROVIDED, FURTHER, that any Asset Disposition
                  pursuant to CLAUSES (i), (ii), (iii), (iv), (v) and (vi) of
                  this proviso shall


                                      -15-
<PAGE>

                  not be included in the calculation of the aggregate net book
                  value of assets sold pursuant to this SECTION 8.4.".

         (g) SECTION 8.5 of the Participation Agreement shall be amended by
deleting SECTION 8.5(v) of the Participation Agreement and replacing it in its
entirety with the following:

                  "(v)  Investments evidenced by the Synthetic Lease
                  Intercompany Note and the Powerton/Joliet Lease Intercompany
                  Notes.".

         (h) SECTION 8.6 of the Participation Agreement shall be amended by
deleting the last sentence and replacing it with the following sentence:

                  "Notwithstanding the foregoing, the Synthetic Lease
                  Transaction, the transactions contemplated by the Synthetic
                  Lease Basic Documents, the Powerton/Joliet Lease Transaction
                  and the transactions contemplated by the Powerton/Joliet
                  Lease Operative Documents shall be deemed not to be a
                  Transaction with an Affiliate for the purposes of this SECTION
                  8.6.".

         (i) SECTION 8.12 of the Participation Agreement shall be amended by
deleting the last sentence and replacing it with the following sentence:

                  "Notwithstanding the foregoing, so long as no Event of Loss or
                  Lease Event of Default shall have occurred and be continuing,
                  Holdings or its Subsidiaries may make a Restricted Payment to
                  Edison Mission Energy on or within 30 days after the date (A)
                  any Powerton/Joliet Lease Intercompany Note Payment is
                  received by Midwest in an amount not exceeding such
                  Powerton/Joliet Lease Intercompany Note Payment (to the extent
                  that the same was not included in any Restricted Payment
                  theretofore made in accordance with this SECTION 8.12 or used
                  to pay Powerton/Joliet Lease Liabilities) and (B) any
                  Synthetic Lease Intercompany Note Payment is received by
                  Midwest in an amount not exceeding such Synthetic Lease
                  Intercompany Note Payment (to the extent that the same was not
                  included in any Restricted Payment theretofore made in
                  accordance with this SECTION 8.12); PROVIDED that, in the
                  event that Midwest pays Incremental Synthetic Lease
                  Environmental Indemnity Payments, the aggregate


                                      -16-
<PAGE>

                  amount of Restricted Payments payable in accordance with this
                  sentence (but not otherwise in accordance with this SECTION
                  8.12) shall be reduced by a like amount.".

         (j) SECTION 8 of the Participation Agreement shall be amended by adding
SECTION 8.14 to the Participation Agreement as follows:

                  "SECTION 8.14 POWERTON/JOLIET LEASE OPERATIVE DOCUMENTS.
                  Holdings shall not, and shall not permit any of its Sub-
                  sidiaries, to agree or consent to any termination, amendment,
                  modification or waiver of (a) Section 18.19 of each of the
                  Powerton/Joliet Lease Participation Agreements, (b) the
                  definition of "Free Cashflow" set forth in the Powerton/Joliet
                  Lease Operative Documents, (c) the Powerton/Joliet Lease
                  Intercompany Notes or (d) or any other provision of the
                  Powerton/Joliet Lease Operative Documents that increases or is
                  reasonably likely to increase the liability, or the
                  obligations, of Midwest (or decreases or is reasonably likely
                  to decrease the liability, or the obligations, of Edison
                  Mission Energy) with respect to the Powerton/Joliet Lease
                  Operative Documents in any material respect.".

         Section 3.  AUTHORIZATION OF AMENDMENT OF FACILITY LEASE AND FACILITY
SUBLEASE.

         (a) Collins Holdings, the Owner Lessor, the Owner Participant and the
Holder Representative hereby authorize amendments to that certain Facility Lease
Agreement (T1), dated as of December 15, 1999, by and among the Owner Lessor,
the Owner Participant and Collins Holdings (as heretofore amended, modified and
supplemented, the "FACILITY LEASE"), substantially in the form of Exhibit A
hereto.

         (b) The Holder Representative, Collins Holdings, the Owner Participant,
the Owner Lessor and Midwest hereby authorize that the amendments to the
Facility Lease authorized by paragraph (a) of this Section 3 will effect
corresponding amendments to the terms of that certain Facility Sublease
Agreement (T1), dated as of December 15, 1999, by and among Collins Holdings,
Midwest and the Owner Lessor (as heretofore amended, modified and supplemented,
the "FACILITY SUBLEASE").


                                      -17-
<PAGE>

                  Section 4. CONSENT/WAIVER. The Owner Lessor, Funding LLC and
the Holder Representative hereby consent to the execution and delivery by
Midwest and ComEd of Amendment No.1 to Collins PPA.

                  Section 5. CONDITIONS PRECEDENT. This Amendment shall not
become effective until the date (the "AMENDMENT EFFECTIVE DATE") on which each
of the following conditions precedent have been satisfied or will be satisfied
contemporaneously with this Amendment becoming effective:

         (a) Delivery to the parties hereto of this Amendment duly executed and
         delivered by each other party hereto;

         (b) Delivery to Owner Lessor, Owner Trustee, Owner Participant, Funding
         LLC, the Midwest LC Issuer, the RCE LC Issuer and the Holder
         Representative of the Powerton/Joliet Lease Operative Documents in form
         and substance satisfactory to the recipients;

         (c) All conditions precedent to effectuate the Powerton/Joliet Lease
         Transaction have been satisfied (including delivery of the ComEd
         Powerton/Joliet Lease Consents) or waived;

         (d) Delivery to the Holdings Collateral Agent of (i) the
         Powerton/Joliet Intercompany Note Pledge Agreement and (ii) the
         Powerton/Joliet Subordination Agreements, each in form and substance
         satisfactory to the recipient;

         (e) The Owner Lessor, Owner Trustee, Owner Participant, Funding LLC,
         the Midwest LC Issuer, the RCE LC Issuer and the Holder Representative
         shall have received opinions, dated the Amendment Effective Date and
         addressed to the recipients from (i) the general counsel to Holdings,
         Midwest and Collins Holdings, (ii) the special New York counsel to
         Holdings, Midwest and Collins Holdings and (iii) the special Illinois
         counsel to the Loan Parties, and (iv) Federal Energy Regulatory
         Commission counsel to the Holdings, Midwest and Collins Holdings. Each
         such opinion shall be in form and substance reasonably satisfactory to
         the recipients;

         (f) Holdings shall have received written confirmation that after giving
         effect to the Powerton/Joliet Lease Transaction, no Debt Rating shall
         fall below the


                                      -18-
<PAGE>

         Debt Rating in effect prior to giving effect to the Powerton/Joliet
         Lease Transaction;

         (g) The representations and warranties of Holdings, Midwest and Collins
         Holdings as set forth in the Participation Agreement, shall be true and
         correct as of the Amendment Effective Date after giving effect to the
         amendments contemplated hereby (unless stated to be given as of an
         earlier date, in which case such representation and warranty shall be
         true and correct only as of such earlier date);

         (h) As of the Amendment Effective Date, no Lease Event of Default, or
         Event of Loss or event that, with passage of time or giving of notice
         or both, would constitute a Lease Event of Default or an Event of Loss,
         shall have occurred and be continuing; and

         (i) Contemporaneously with this Amendment becoming effective, the
         Holder Representative shall have received confirmation that Edison
         Mission Energy has used the proceeds of the Powerton/Joliet
         Intercompany Notes to repay in full Indebtedness of Edison Mission
         Energy (including, without limitation, the repayment in full of its
         obligations under the Credit Agreement dated as of December 15, 1999
         among Edison Mission Energy, the commercial lending institutions party
         thereto and The Chase Manhattan Bank, as Administrative Agent and the
         termination of related commitments).

                  Section 6. MISCELLANEOUS. Except as expressly amended hereby,
all of the terms and provisions of the Participation Agreement are and shall
remain in full force and effect. This Amendment may be executed in any number of
counter parts, all of which taken together shall constitute one and the same
instrument and any of the parties hereto may execute this Amendment by signing
any such counter part. This Amendment shall be governed by, and construed in
accordance with, the law of the State of New York.


                                      -19-
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
executed and delivered by their respective officers thereunto duly authorized.

                                    COLLINS HOLDINGS EME, LLC

                                    By:  /s/ John P. Finneran, Jr.
                                         -------------------------
                                         Name:    John P. Finneran
                                         Title: Vice President
                                         Date:    August 24, 2000

                                    COLLINS TRUST I

                                    By:  Wilmington Trust Company,
                                         not in its individual capacity but
                                         solely as Owner Trustee

                                    By:  /s/ James P. Lawler
                                         -------------------
                                         Name:    James P. Lawler
                                         Title:  Vice President
                                         Date:   August 24, 2000

                                    WILMINGTON TRUST COMPANY,
                                    not in its individual capacity, except
                                    as expressly provided herein, but
                                    solely as Owner Trustee

                                    By:  /s/ James P. Lawler
                                         -------------------
                                         Name:    James P. Lawler
                                         Title:  Vice President
                                         Date:   August 24, 2000

                                    COLLINS GENERATION I, LLC

                                    By:  /s/ Christopher P. Kelleher
                                         ---------------------------
                                         Name:    Christopher P. Kelleher
                                         Title:   Manager
                                         Date:    August 24, 2000
<PAGE>

                                    EDISON MISSION MIDWEST HOLDINGS CO.,

                                    By:  /s/ Gary Garcia
                                         -------------------------
                                         Name:    Gary Garcia
                                         Title:   Vice President
                                         Date:    August 24, 2000



                                    MIDWEST GENERATION, LLC

                                    By:  /s/ Gary Garcia
                                         -------------------------
                                         Name:    Gary Garcia
                                         Title:   Vice President
                                         Date:    August 24, 2000


                                    CITIBANK, N.A.
                                    not in its individual capacity, but
                                    solely as Holder Representative

                                    By:   /s/ Jenny Cheng
                                         -------------------------
                                         Name:    Jenny Cheng
                                         Title:   Vice President
                                         Date:    August 24, 2000



                                    MIDWEST FUNDING LLC


                                    By: /s/ Peter H. Sorensen
                                         -------------------------
                                        Name: Peter H. Sorensen
                                        Title: President
                                        Date:  August 24, 2000

<PAGE>

                                    BAYERISCHE LANDESBANK INTERNATIONAL S.A.,
                                    a banking institution organized under the
                                    laws of Luxembourg, as issuer of the Midwest
                                    Letter of Credit


                                    By:  /s/ Herbert Weynand
                                         --------------------------------
                                         Name: Herbert Weynand
                                         Title: Head of Corporate Banking
                                         Date:  August 11, 2000


                                    By:  /s/ Peter Lang
                                         --------------------------------
                                         Name: Peter Lang
                                         Title:  Group Head of Corporate Finance
                                         Date:  August 11, 2000



                                    BAYERISCHE LANDESBANK GIROZENTRALE,
                                    as issuer of the RCE Letter of Credit


                                    By:  /s/ Dietmar Rieg
                                         ----------------
                                         Name: Dietmar Rieg
                                         Title: First Vice President
                                         Date:  August 11, 2000


                                    By:  /s/ Cornelia Wintergerst
                                         ------------------------
                                         Name: Cornelia Wintergerst
                                         Title: Vice President
                                         Date:  August 11, 2000
<PAGE>

                                                                       EXHIBIT A
                                   FORM OF AMENDMENT TO FACILITY LEASE AGREEMENT

                                  AMENDMENT TWO

         AMENDMENT TWO (this "AMENDMENT") dated as of August __, 2000 by and
between Collins Trust I (the "OWNER LESSOR") and Collins Holdings EME, LLC (the
"FACILITY LESSEE").

         WHEREAS, the Owner Lessor and the Facility Lessee have entered into
that certain Facility Lease Agreement (T1), dated as of December 15, 1999 (as
amended, supplemented or otherwise modified from time to time and in accordance
with the provisions thereof, the "FACILITY LEASE").

         WHEREAS, the Owner Lessor, the Facility Lessee, Wilmington Trust
Company, Collins Generation I, LLC, Edison Mission Midwest Holdings Co.,
Midwest, Midwest Funding LLC, Bayerische Landesbank International S.A.,
Bayerische Landesbank Girozentrale and Citibank, N.A. have entered into that
certain Participation Agreement, dated as of December 15, 1999 (as amended,
supplemented or otherwise modified from time to time and in accordance with the
provisions thereof, the "PARTICIPATION AGREEMENT").

         WHEREAS, Midwest desires to enter into the Leveraged Lease Transaction;

         WHEREAS, Midwest has requested, and the Owner Lessor and the Facility
Lessee have agreed, to amend and waive certain provisions of the Facility Lease
so as to permit the Leveraged Lease Transaction; and

         WHEREAS, Midwest has requested, and the other parties to the
Participation Agreement have agreed, in that certain Amendment Three, dated as
of August __, 2000, by and among the parties to the Participation Agreement,
("AMENDMENT THREE TO THE PARTICIPATION AGREEMENT"), to amend and waive certain
provisions of the Participation Agreement so as to permit the Leveraged Lease
Transaction;

         NOW, THEREFORE, the parties hereto agree as follows:

<PAGE>

         Section 1. DEFINITIONS. Except as otherwise defined in this Amendment,
terms defined in the Facility Lease are used herein (and in the introductions
and recitals hereto) as defined therein.

         Section 2. AMENDMENT TO THE FACILITY LEASE. Subject to the satisfaction
of the conditions precedent specified in Section 3 below, but effective as of
the Amendment Effective Date, the Facility Lease shall be amended as follows:

      (a) SECTION 16(h) of the Facility Lease shall be amended by inserting the
      following phrase immediately after the phrase "but excluding obligations
      arising under the Operative Documents" in the second line of SECTION 16(h)
      of the Facility Lease:

         ", Synthetic Lease Liabilities, Powerton/Joliet Lease Liabilities".

      (b) SECTION 16 of the Facility Lease shall be amended by adding SECTIONS
      16(v), 16(w) and 16(x) to the Facility Lease as follows:

         "(v) any of the Powerton/Joliet Lease Trusts (or the related Lease
         Indenture Trustee (under, and as defined in the related,
         Powerton/Joliet Lease Operative Documents) should have commenced to
         exercise remedies in accordance with Section 17 of the Powerton/Joliet
         Leases to terminate any of the Powerton/Joliet Leases and repossess any
         of the Powerton/Joliet Lease Assets.

         (w) Edison Mission Energy shall fail to make payment or fail to perform
         its obligations under any Powerton/Joliet Lease Guarantee or any
         Powerton/Joliet Lease Intercompany Note within five Business Days after
         any such payment becomes due in accordance with the terms thereof or
         hereof.

         (x) any of the Powerton/Joliet Lease Guarantees or the Powerton/Joliet
         Lease Intercompany Notes is declared unenforceable or is terminated, or
         Edison Mission Energy or any Powerton/Joliet Trust shall assert that
         any of the Powerton/Joliet Lease Guarantees or the Powerton/Joliet
         Lease Intercompany Notes to which it is a party shall no longer be in
         full force and effect.".

         Section 3. CONDITIONS PRECEDENT. This Amendment shall not become
effective until the date (the "AMENDMENT EFFECTIVE DATE") on which each of the
following conditions precedent has been satisfied or will be satisfied
contemporaneously with this Amendment becoming effective:

<PAGE>

      (a) Delivery to the parties hereto of this Amendment duly executed and
      delivered by each other party hereto;

      (b) All conditions precedent contained in Section 4 of Amendment Three to
      the Participation Agreement have been satisfied.

         Section 4. MISCELLANEOUS. Except as expressly amended hereby, all of
      the terms and provisions of the Facility Lease are and shall remain in
      full force and effect. This Amendment may be executed in any number of
      counterparts, all of which taken together shall constitute one and the
      same instrument and any of the parties hereto may execute this Amendment
      by signing any such counterpart. This Amend ment shall be governed by, and
      construed in accordance with, the law of the State of New York.

<PAGE>

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed
and delivered by their respective officers thereunto duly authorized.

                                    COLLINS HOLDINGS EME, LLC


                                    By:
                                        ----------------------------------
                                         Name:
                                         Title:
                                         Date:    August     , 2000


                                    COLLINS TRUST I

                                    By:  Wilmington Trust Company,
                                         not in its individual capacity but
                                         solely as Owner Trustee


                                    By:
                                        ----------------------------------
                                         Name:
                                         Title:
                                         Date:   August     , 2000